The theory and practice of infant feeding, with notes on development

Front matter

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Preface To Third Edition

SINCE the second edition of this book was published much advance has been made in the science and art of infant feeding. It has become recognized that there is vastly more to artificial infant feeding than adjusting the quantitative differences between cow's milk and breast milk and that a new system of presenting the subject was necessary.

Instead of making the superficial chemical composition of mother's milk the starting point* and striving to make an artificial human milk, as has been the case, it is more and more coming to be seen that the infant is subject to the general laws of animal life and that often these may be conformed to in a number of apparently different ways.

Methods formerly condemned as unscientific, although they gave good results, are now seen to be in strict accordance with natural biological laws, while some procedures formerly taught as scientific have been shown to be the reverse.

The chapters on practical feeding have been rewritten and broadened in this edition and sections on the principle of top milks and the standardization of gruels have been added.

It is gratifying to the author to feel that his efforts in vi PREFACE TO THIRD EDITION.

treating infant feeding from the standpoint of biology have been recognized as of value in placing this important subject in line with general scientific development. Henry Dwight Chapin, M.D.

February i, 1909.

Preface To Second Edition

WHEN the first edition of this book was issued it was thought that artificial infant feeding could not advance much beyond its position at that time, unless the scope of study was broadened. The correct basis of the science of artificial infant feeding was then thought by many to be an adjustment of the quantitative differences of cow's milk and breast milk, and the alteration of the reaction of cow's milk to litmus paper by the addition of lime water or bicarbonate of sodium. A purely chemical basis was sought to be established.

The author has never felt that this was a correct view of the subject, and, while accepting all that was an advance, has thought that the suitability of a food for infants was not a matter of its chemical composition alone. It is gratifying to find that the most experienced investigators of the problems of animal nutrition have adopted this view with regard to the feeding of all species of animals, and that adaptation of the food to the particular species of animal according to its digestive apparatus is a recognized first principle of feeding.

Since the first edition appeared, much work has been done with modern and improved methods in the comparative chemical examination of breast milk and cow's milk, with the result that many of their supposed differences viii PREFACE TO SECOND EDITION.

have disappeared. The supposed distinctive difference of breast milk being alkaline and cow's milk acid in reaction, has been shown to be non-existent and due to the use of improper and unsuitable methods of determining the reaction. So this supposed fundamental difference proves to be of little significance and has lost its importance.

Very important discoveries pertaining to cow's milk have recently been made, among which are some of the changes that take place in the digestion of milk and the effect of the addition of alkalies on the digestion of milk, all of which tends to make clearer the physiology of milk and the true principles of artificial infant feeding.

The book has been carefully revised and some portions have been re-written and extended, and it is hoped that the second edition will more clearly than the first show what a peculiar and distinct position artificial infant feeding holds in the subject of dietetics.

Henry Dwight Chapin, M.D.

51 West Fifty-First Street, New York, June, 1904.

Preface

THE great and increasing importance the subject of artificial infant feeding is assuming in all classes of society has led the author to believe there might be a field for a work on this subject that, instead of laying down rules and formulas for preparing food supposed to be suitable for infants of different ages, aimed rather to show the fundamental principles of growth, nutrition, and digestion during infancy, and then leave it to the physician to apply these principles. The discovery that the law of conservation of energy applies to animal life has made the nutrition of adults almost an exact science. In infant feeding there are other problems than mere nutrition that must be considered. The great mass of literature on infant feeding that has appeared within the past few years has been devoted in the most part toward producing a substitute food that should chemically approximate human milk. In this book the special function of milk in developing the digestive tract of the young animal is treated, the author believes, for the first time, and it is more than likely that further study along this line may necessitate greater or less modification of the conclusions here drawn.

x PREFACE.

American authorities on milk have been followed because the conditions under which milk is produced and marketed in America are so different from those of Europe that many statements found in European medical journals concerning milk supplies must be inapplicable to the work of a majority of American physicians, and besides, the greatest advances in dairying and knowledge of the chemistry of milk have been made in America.

In the Appendix will be found a list of works and articles from which data have been drawn. The material of the book has been divided into four parts, each being as complete in itself as the subject will allow. By a system of cross references it is aimed to bring the principles involved and their application in close connection.

The author wishes to acknowledge his indebtedness to Profs. W. A. Henry, S. M. Babcock, and F. W. Woll, and Major H. E. Alvord for valuable information; to Professor H. W. Conn for the chapter on Bacteriological Examination of Milk; to Dr. Hrdlika for making anthropological measurements, assisted by Dr. Pisek, and to Dr. Pisek for securing the photographs of infants. The thanks of the author are also extended to the publishers for courtesies rendered during the preparation of

the volume.

Henry Dwight Chapin.

August i, 1902.

Chapter I. General Introduction

Two controlling factors are present in all life— heredity and environment. At the birth of the individual the first has done its best or worst and cannot be reckoned with in the sense of being influenced. Its activity has been through long reaches of past time, and the laws of its operation are but imperfectly understood. The question of environment, being of the present and to a certain extent possible of control, assumes the greatest importance. While from a purely biologic standpoint heredity may appear to be the most important influence, yet in the scheme of evolution the higher the animal the more important becomes environment. This is specially emphasized in man by the prolongation of the period of infancy. John Fiske was the first to elaborate this fruitful view of one of the fundamental laws of higher evolution, that not only throws a strong light on the methods of evolution, but lays the greatest importance on the period of infancy as influencing the future development and usefulness of the animal. This long period of helpless infancy is a time of extreme plasticity, when the career of the individual is no longer predetermined by the career of its ancestor. One generation of the lower animals is almost an exact reproduction of tin; preceding one. The young animal is born pretty fully formed, and can lookout for itself almost from the beginning, independently of the parent. The longer the infancy of an animal becomes, the greater the period of its teachability, and a slow growth means an increase in capacity for development and all the higher prerogatives.

Thus the higher apes have a helpless babyhood, when for two or three months they are unable to feed themselves or move about independently of the parent. The human infant is distinguished from the highest of the lower animals by the very long duration of helpless infancy and the marked increase in the size of the brain, and particularly in the extent of its surface. There is here a great increase in the size and complexity of brain organization that takes place largely after birth. Accompanying the rapid growth of the nervous system is that of the skeleton and various visceral organs. During the first two years of life the brain not only doubles in weight, but increases marvellously in its convolutions and complexity. The infinite distance between man and the lower animals consists in the fact that in the former natural selection confines itself principally to the surface of the brain, and requires a long period of helpless infancy for this highly plastic work to be properly started and developed. Inherited tendencies are there, but the proper environment counts for much in this work so potent in future possibilities. It is evident that, correlated with his long period of helpless infancy, there must be a time of maternal care and watchfulness, if the race is to exist in health and vigor. Knowledge is required as well as care, for mistakes made at this time can never be completely corrected. The first few years of life are, biologically speaking, the most important ones we live. The begin-

GENERAL INTRODUCTION. 3

ning organism has at this time stamped on it the possibilities of future vigorous life or of early degeneration and decay. Hence a careful study and understanding of all the phases of infancy are of the greatest importance alike to physicians and parents. At a period of such rapid growth and development, it is evident that proper nutrition must play the leading part. All competent observers are agreed that the best nourishment for a baby naturally comes from its own mother. Unfortunately a large number of mothers, from physical or social causes, are unable to give this proper nutriment. It appears to be one of the penalties of modern civilization that an increasing number of women cannot or will not nurse their offspring. Hence it is that in recent years a large amount of study and labor has been expended upon substitute infant feeding. Great advances have been made, but it must be confessed that the results are not always proportionate to the labor expended. The tendency appears to be to a greater degree of complexity and elaborateness than the average practitioner and mother can understand or apply. Hence discouragement is apt to follow, and a return to old and haphazard methods if the immediate results are fairly satisfactory. Proprietary infant foods also profit by this feeling of confusion, as they often agree with the baby for the time being, although not containing the proper ingredients for healthy growth and nutrition.

The effort to place the food principles of milk in their proper ratio has led to " percentage feeding," which represents a decided advance, but has been pushed to an extreme that is difficult, if not impossible, to apply. The author has long thought that some of the benefits of this method of feeding come more from the care and cleanliness with which the milk is handled than from the minute changes in the percentages that are often advised; indeed, analysis sometimes shows that these fine changes are more on paper than in the ingredients of the milk. It is well to think in percentages and be as exact as possible in feeding a baby, but the problem has not thus been completely solved, when we are putting the milk of one species of animal into the stomach of another species having a different digestive apparatus.

The greatest problem in the life of any animal is that of securing sufficient food. All forms of animal life demand the same ultimate food elements, so that really their great diversification is along the lines of methods and organs provided by nature for securing and digesting food. While the outward forms of animals are apparent to every casual observer, their digestive systems, which are hidden, are as much diversified as their more apparent shapes, and are as much adapted for the digestion of a particular food as the outward organs are for securing it. Hence the milk of each type of animal must be studied from the standpoint of its special adaptation to the digestive tract for which it is intended: a hard curding milk is intended for a polygastric digestive tract that can properly deal with it ; a soft curding milk for a monogastric digestive tract. These differences assume the greatest importance when the milk of one species of animal is fed to another species. This subject will be carefully considered in the present work, as it has a direct practical bearing upon successful infant feeding. While percentage feeding and the physical differences in the same

GENERAL INTRODUCTION. 5

ingredients in the milks of different species are of great importance, the preliminary question of how to get clean, fresh cow's milk is the fundamental one. Too little attention has been given to this question in works on infant feeding. It will here be treated at some length and. in detail, as the observations of the author lead him to believe that future advances in infant feeding must be principally along this line. In order to insist upon pure, clean milk, the physician must know how it is produced and insist upon proper conditions. It can easily be produced anywhere, if the details are properly carried out ; and this does not require an elaborate, expensive plant, as many believe. It calls for knowledge on the part of the physician or sanitarian that can easily be conveyed to the farmer and dairyman. This is the first requisite in successful infant feeding:.

Chapter II. How To Approach The Subject Of Infant Feeding

i. Any one called on to feed an infant during the period it is normally nourished by its mother has a great responsibility thrust upon him and one not to be assumed lightly or without preparation. Too many are satisfied when something that is retained in the stomach and causes a gain in weight is found, no thought being given to whether the food contains material out of which healthy tissue can be formed.

It has often been stated that an artificial food for infants should contain nothing that is not found in mother's milk, and that it should contain just what is found in mother's milk. To prove the suitability of various substitutes for mother's milk chemical analyses of both have been published, to show how closely the substitutes approximate mother's milk. At first sight this seems a rational procedure, but when it is remembered that there is no difference between a diamond and a piece of charcoal chemically, and that mixtures of butter, cheese, sugar, salts, and water, or of beef suet, raw beef, sugar, salts, and water, can be made which when analyzed by the usual methods will show the same composition as mother's milk, the fallacy of judging the suitability of a food for an infant, or for an adult for that matter, by its chemical

HOW TO APPROACH INFANT FEEDING. 7

analysis only will be apparent. Physiological chemistry has not advanced sufficiently to make it a safe guide by itself.

In feeding an adult it is only necessary to furnish enough food to repair waste. In feeding an infant not only must waste be repaired, but material to build up new tissue must be supplied, or the infant cannot grow normally. The whole future of the infant may depend on what kind of food is supplied it up to the time it can take table food. Then the danger of an insufficient supply of tissue-building food is not so great.

The ability to resist disease depends largely on having the cells in which the vital processes take place plentiful in number and well nourished. These cells form a large portion of all the organs and tissues of the body, and if the material needed to build cells is not furnished in sufficient quantity, the gain in weight, if there is any, will be mostly fat and water. It does not follow that because a baby is fat that it is strong or healthy. The cells may be actually starving and so few in number that the body may be likened to a large showy house built with very light timbers, all ready to collapse under a slight strain (128).

Not only must the food for an infant contain material from which cells may be built up, but the material must be in such a condition that the infant can digest it without undue effort. Furthermore the food must be cheap enough to be within the reach of all and easily prepared.

Naturally the milk of the cow or of some other animal is suggested, but experience shows that these milks do not agree with infants generally, unless in some way changed or modified, the great difficulty being the inability of the infant to digest the elements of the milk of which cells are composed. Undoubtedly the milk of all animals contains the materials necessary to build up strong healthy cells and tissues, as no young animal thrives as well on anything else as it does on its mother's milk or on the milk of some other animal of the same species. At first thought it seems strange that the milk of one species of animal is not suitable for the young of another species ; but when the mode of living, and the digestive systems, rate of growth, and stage of development at birth of the different species are compared, it will be found that the milk of each animal is adapted to its own digestive system, rate of growth, and state of development ; also that the milk of the mother behaves in the young animal's stomach very much as the food of the mother behaves in her stomach. The young animal is being educated to digest in the same manner as it will when it is grown. This subject will be gone into in detail in subsequent chapters, as it has been given very little or no consideration by writers on infant dietetics.

Before there can be intelligent food prescribing there must be a knowledge of the substances needed to construct cells and keep them well nourished ; of the sources from which these substances may be obtained; of how they are transmitted to the cells through the blood stream after digestion and absorption ; of the nature of digestion and the digestive systems of different animals; of what changes take place in the food in the cells, and what becomes of the waste products. Then only can feeding be taken up in a scientific manner.

The problem of feeding infants in all classes of society

HOW TO APPROACH INFANT FEEDING. 9

calls for ability to produce a satisfactory food in a simple and inexpensive manner. This necessitates a knowledge of raw food materials, how they are produced, and the best means of preserving them from deterioration and infection by disease or other kinds of germs, and how these food materials, no matter what their source, may be best prepared for digestion by the infant.

Before taking up methods of preparing food for infants, some space will be devoted to physiological chemistry, physiology of young animals, comparison of the digestive systems and milks of various animals, the production of milk and other raw food products, and methods of analyzing and testing food materials.

Chapter III

ANIMAL CELL— ITS CONSTITUENTS— GROWTH A PROCESS OF CELL DIVISION— YOUNG ANIMAL RUDIMENT OF PARENT.

2. The unit of the animal organism is the cell. In the cells all the vital processes take place. They are the chemical laboratories of the body and are the ultimate destination of all the food that is digested. The lowest torms of animals are single-cell animals. These single-cell animals carry on all of the chemical processes that highly organized animals carry on. Every part of a single-cell animal can digest food, every part can breathe, every part can feel, and every part can think. All the faculties of an animal are bound up in one cell. The starting-point in the development of any animal is a single cell about one hundred and twenty-fifth of an inch in diameter. This cell divides and forms two cells, these divide, and so on. This increase in number of cells constitutes growth (Figs, i and 2). An organized animal, therefore, is a nation of cells, divided into many executive branches or organs. Certain organs are adapted for securing food, others for digesting it, and others for throwing off waste products. Then there is the circulatory system that carries the necessary food to every cell in the body. All cells are in some way in communication with the blood supply and able to select from it food particularly suited to their needs. The cells of the bones select mineral matter from the blood, other cells select other matter

ANIMAL CELL. n

that contains little earthy material. What none of the cells wants is excreted in the urine. It is absolutely beyond human power to control the food requirements of a

Fig. i. — Section of Ovum. (Jewett.) Shows the original cell or starting point of a.i animal.

cell ; if it does not want particular food substances that are in the blood it will not take them, and if the food the

Fig. 2.— Illustration of Cell Division or Growth. (Allen Thompson, after E. Van Beneden.)

cell does want is not supplied, starvation of the cell is sure to result. Therefore a study of the cells is necessary to show their food requirements.

The cells are so small that they cannot be examined except by the aid of a microscope, but as they make up a large part of the tissues of the body, a study of the tissues is practically a study of the cells.

To the eye a piece of flesh consists of muscle, connective tissue, cartilage, fat, and possibly mucous membrane, skin, blood-vessels, and nerves.

The chief mass of these tissues, with the exception of water and fat, is called protein substance — the word protein meaning "/ take the first place" All protein substance contains carbon, hydrogen, oxygen, and nitrogen. Mostoi it contains in addition sulphur, and portions contain also phosphorus and iron. While the quantities of these elements vary somewhat, they are fairly constant in all of the tissues, but a chemical analysis of protein would not tell whether it came from skin, mucous membrane, or muscle. Other means of examining tissues had to be devised. These consist of extracting the tissues with various solvents. By this process various forms of protein can be separated to a certain extent. The principal groups of protein substances so separated are:

(i) Albumins and globulins, containing carbon, hydrogen, oxygen, nitrogen, and sulphur.

(2) Nucleo-albumins, containing carbon, hydrogen, nitrogen, oxygen, sulphur, and also phosphorus and iron.

There are many forms of protein that are included in these divisions; for instance:

White of egg is a mixture of albumin and globulin.

Casein of milk (curd) is a nucleo-albumin.

Another class of substances which contain carbon, hydrogen, oxygen, and nitrogen, but which are not protein

ANIMAL CELL. 13

substances, can be separated from animal tissues. These are called extractives or meat bases. The extracts of meat for making beef teas, sold in jars, which are claimed to represent ten to twenty times their weight 'of meat, are "extractives" (no).

Fat, which is composed of carbon, hydrogen, and oxygen only ; lecithin, a kind of fat which contains also phosphorus and nitrogen, found particularly in the brain and nerves ; and glycogen or animal starch, composed of carbon, hydrogen, and oxygen, but in proportions different from those in fat, can also be separated from animal tissues.

Mineral substances found in the tissues are thought to be combined with the protein substances and not to exist in a free state.

3. In examining cells under a microscope, it is found that a certain portion of each cell — the nucleus — contains iron and phosphorus, and that the albumins and globulins which do not contain iron and phosphorus serve more as cell food than as cell builders. Lecithin and glycogen seem to be found in all cells.

There can be no cell division or growth unless the nucleus of the cell first divides, and, as iron and phosphorus are contituents of the nuclei of cells, there can be no cell growth unless food containing iron and phosphorus is furnished. This has been proved by experiment.

The materials necessary to build up cells must be found in eggs, as in an egg there is a single cell that begins to divide and ends by changing the contents of the shell into a live bird. The germinal cell is situated near the yolk, which is used up first, and then the white is drawn on. The yolk is rich in protein containing phosphorus and iron, lecithin, fat, and mineral matter; while the white of the egg, which is about eighty-five per cent water, contains almost nothing that could be used to create cells (2).

4. Up to the time an animal is born it is nourished by the blood stream of its mother, so all the elements for the developing animal must come originally from the mother's food. It would be expected that animals that feed on flesh, as cats and dogs, would be able to supply the materials needed to construct animal tissue ; but animals that feed exclusively on vegetable substances, as cows, sheep, and horses, also have no difficulty in constructing animal tissue. In fact, most of the meat supply of the world is the flesh of animals that live exclusively on vegetable substances, so the only conclusion is that the vegetable kingdom must be able to supply all the materials necessary to form animal tissue.

Examination of hay, wheat, oats, barley, corn, beans, etc., shows them to consist principally of carbohydrates which contain only carbon, hydrogen, and oxygen. Cellulose, or the skeleton of plants, starch, and sugar are typical carbohydrates. Paper is made of the cellulose or cells of wood or straw. Potatoes and cereals contain large quantities of starch, and beets, sugar cane, and maple trees supply sugars. Starch and sugar are the stored-up food of plants. Vegetable tissues contain also small quantities of fat and lecithin and substances containing carbon, hydrogen, oxygen, nitrogen, and also sulphur, phosphorus, and iron, called vegetable protein. It is these substances that are converted into animal cells. Gluten or the sticky, stringy part of bread dough is a familiar

ANIMAL CELL. 15

form of vegetable protein. Chemically there is little difference between gluten and lean meat.

There is one important fact to be remembered : plants have the ability to take water, mineral matter and gases from the soil and air and combine them into proteid, fat, and carbohydrates. Animals cannot do this nor can they change fat and carbohydrates into proteid, but must take these three substances from the vegetable kingdom and elaborate them for their own particular uses; so a perfect food must contain proteid, fat, and carbohydrates in proportions suitable to the needs of each particular animal.

It is evident that a cat or dog would starve if fed hay and grass, and that a horse or cow would not as a rule thrive on raw meat. Human beings feed on meat and vegetable substances, but not in the condition in which the lower animals eat them. They must be prepared by a cooking process before the human digestive apparatus can act to advantage. This forces the conclusion that the digestive system of each kind of animal must be particularly suited to its natural food. As young animals are miniatures or rudiments of their parents, their digestive systems must be in a general way like those of their parents, so it would be natural to suppose the mother's milk would be particularly suited to the young animal's digestion, and that the milk of one kind of animal would not suit the young of another kind any more than the food of a cat would suit a cow or a horse. It is the substitution of some other milk that causes so much trouble in infant feeding. Chemistry has never been able to show why this substitution causes trouble. The answer has been hinted at, — different digestive systems. In the following chapters this important subject will be treated.

Chapter IV

OBJECT AND PROCESSES OF DIGESTION- MECHANISM AND COMPARISONS OF DI- GESTIVE TRACTS.

5. The object of digestion is to separate from the food that is eaten those portions that will serve as nutriment to the organism from those that are useless, and to put them into soluble, absorbable forms, so that the blood can carry them to every part of the body.

The process of digestion consists of two distinct parts: (1) a mechanical part, and (2) a chemical part. The mechanical part consists of grasping, tearing, chewing, or grinding the food ; the chemical part in the solvent action of the various digestive juices.

The chemical changes that take place in a particular kind of food during digestion are practically the same in all forms of animal life, but the mechanism of digestive tracts varies greatly, and the kind of digestive juices that are secreted depends largely on the natural food of the animal. All animals must have protein in some form and all have digestive jriices that will digest it, while some animals have in addition digestive juices that will digest many other substances. A clog whose principal food is animal protein (meat) does not need a digestive juice that will soften hay or grass, and does not have it. A horse or cow needs a digestive juice that will soften and digest